183 is a perfect totient number, a number that is equal to the sum of its iterated totients. Because 183 = 13 2 + 13 + 1 {\displaystyle 183=13^{2}+13+1}, it is the number of points in a projective plane over the finite field Z 13 {\displaystyle \mathbb {Z} {13}}. It is a repdigit in tredecimal (11113). 183 is the fourth element of a divisibility sequence 1 , 3 , 13 , 183 , … {\displaystyle 1,3,13,183,\dots } in which the n {\displaystyle n}th number a n {\displaystyle a{n}} can be computed as a n = a n − 1 2 + a n − 1 + 1 = ⌊ x 2 n ⌋ , {\displaystyle a_{n}=a_{n-1}^{2}+a_{n-1}+1={\bigl \lfloor }x^{2^{n}}{\bigr \rfloor },} for a transcendental number x ≈ 1.38509 {\displaystyle x\approx 1.38509}. This sequence counts the number of trees of height ≤ n {\displaystyle \leq n} in which each node can have at most two children
